Downstream piston-type compressed-gas circuit interrupters

ABSTRACT

A piston-type of gas-blast circuit interrupter provides a cavitation region downstream of a moving tubular contact to cause exhausting flow of gas therethrough. Means are provided for a fixed open gap distance between the separated contacts to avoid excessive arc lengthening. Cooling means are employed within the moving tubular contact and downstream thereof to prevent gasclogging action and to protect a rolling rubber diaphragm sealing the moving piston.

United, States Patent Winthrop M. Leeds; Harvey E. Spindle, Pittsburgh, Pa. 625.212

Mar. 22, 1967 Jan. 19, 1971 Westinghouse Electric Corporation Pittsburgh, Pa.

a corporation of Pennsylvania Inventors Appl. No. Filed Patented Assignee DOWNSTREAM PISTON-TYPE COMPRESSED GAS CIRCUIT INTERRUPTERS 8 Claims, 6 Drawing Figs. u.s.c| zoo/14s Int. Cl H0lh 33/70 Field of Search 200/ 148,

Primary Examiner-Robert S. Macon Arrorneys-A. T. Stratton, Clement L. Mc Hale and Willard R.

Croat AFSTRACT: A piston-type of gas-blast circuit interrupter provides a cavitation region downstream of a moving tubular .contact to cause exhausting flow of gas therethrough. Means are provided for a fixed open gap distance between the separated contacts to avoid excessive are lengthening. Cooling means are employed within the moving tubular contact and downstream thereof to prevent gas-clogging action and to protect a rolling rubber diaphragm sealing the moving piston.

ATENT ED JANISIQW r v "sum: org

. PRESSURIZFP i 4-,- I l 1 1 4 4 COMPRES$ED\ I AIR WITNESSES i y, 1 Winthrop M. Leeds M 0:6 Horyey E; Spindle DOWNSTREAM PISTON-TYPE COMPRESSED-GAS CIRCUIT INTERRUPTERS CROSS-REFERENCES TO RELATED APPLICATIONS The present application has relationship with pending application filed Nov. 29, I966, Ser. No. 597,690, now US. Pat.

. No. $538,282 by WinthropM. Leeds entitled Fluid-B last Circuit Interrupter With High-Current Blasts to Atmosphere, and assigned to the assignee of the instant-application. Also,

the subject matter of this invention has relation to application of the instant application, there is illustrated and described a compressed-gas downstream piston-type of circuit interrupter, in which a movable tubular contact, secured to a piston, separates from a stationary contact structure within a pressurized chamber; and the opening movement the piston within an operating cylinder provides a cavitation effect to thereby draw'arc extinguishing gas from the'pressurized chamber and the opening movement through the movable tubular contact and into the cavitation region behind themoving piston; The

flow of arc-extinguishing gas through the movable tubular contact and into intimate engagement with the established are rapidly effects the extinction thereof. Certain improvements in this type of breaker are set forth in US. Pat. application filed Nov. 29, I966, Ser. No. 597,690 by'the same inventor, and likewise assigned to the same assignee.

Three problems have appeared in the particular construction set forth in the aforesaid patent applications. These problems may be enumerated as follows: (1 Since the moving contact is attached to the piston, the arc is unnecessarily lengthened beyond the optimum gap for interruption. (2) The expanding hot gas downstream from the arc tends to clog the hollow moving contact passage. (3) The piston-accelerating springs and rolling diaphragm are exposed to high-temperature gas. It is, accordingly, an object of the present invention I to provide an improved interrupting construction of the downstream compressed-gas type, which overcomes the above difficulties and contains other novel and useful features as well.

SUMMARY OF THE INVENTION A general object of the presentinvention is to provide an improved downstream piston-type of compressed-gas circuit interrupter in which the arc is established to an optimum length suitable for rapid arc interruption.

, Still a further object of the present invention is to provide a novel cooling structure so situated as to rapidly effect cooling of the hot gases drawn into the moving tubular contact structure by the cavitation action during the opening operation.

Still a further object of the present invention is to provide an improved contact-spring construction, which enables the rapid closing of the circuit interrupter should the pressure within the pressurized region enclosing the separable contacts become lost to thereby prevent sparkover between the separable contacts during the opening operation.

Still a further objectof the present invention is to protect and shield the piston-accelerating springs and rolling diaphragm from the high-temperature hot arc gases.

Still a further object of the present invention is the provision of a novel contact structure for a downstream piston-type of compressed-gas circuit interrupter.

An ancillary object of the present invention is the provision,

of a double-break type of circuit interrupter of the foregoing type in which simultaneous contact action may be effectively achieved.

In accordance with one embodiment of the present invention, there is provided a stationary contact structure disposed within a pressurized chamber, which is cooperable with a movable tubular contact secured to a piston operable within an operating cylinder, and is closed by the admission of compressed gas, for instance compressed air, in backof the piston. By a reduction of the operating gas pressure on the back side of the operating piston, the pressurized medium withinthe contact chamber is forced through the movable tubular separating contact into the cavitating region on the other side of the operating piston, to thereby rapidly effect arc extinction by the flow of high-pressure gas through the movable tubular venting contact to a cavitation region.

In accordance with another feature of the present invention, a fixed contact separation is achieved by the use of auxiliary stationary tubular contact structure, which insure that the arc is not lengthened beyond its most effective arc length during interruption.

In accordance with a further object of the present invention a pair of serially related, separable contact structures are provided, each of which has a movable tubular contact secured to a piston operable within an operating cylinder, and a simultaneous reduction of compressed gas pressure behind the pistons simultaneously effects opening of the two sets of separable contact structures to thereby establish a pair of scrially related arcs.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view, partially in vertical section, of a downstream piston-type of compressed gas circuit interrupter embodying features of the present invention, the contact structure being illustrated in the closed-circuit position;

FIG. 2 is a fragmentary enlarged view of the separable contact structure of FIG. 1, the contact structure being shown in its separated arcing position;

FIG. 3 is a somewhat diagrammatic fragmentary view of the valve-operating arrangement for the circuit interrupter of FIGS. 1 and 2;

FIG. 4 is an enlarged vertical sectional view taken through a modified-type of contact structure, which may be substituted for the contact structure illustrated in FIGS. 1 and 2, the FIG. illustrating the contact structure in the separated arcing position;

FIG. 5 is another modified-type of separable contact structure, which may be substituted for the contact structure of FIGS. 1 and 2; again the separable contact structure being illustrated in the arcing position; and

FIG. 6 is a vertical sectional view of a modified-type of double-break downstream-type of compressed-gas circuit interrupter illustrating the use of two serially related downstream piston-types of separable contact structures, the contact structures being illustrated in the closed-circuit position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, and more particularly to FIGS. 1-

3 thereof, the reference numeral 1 generally designates a Surmounted upon the grounded upstanding framework and I reservoir 3 is a metallic valve housing 4 enclosing a valve operating arrangement 5 (FIG. 3) for the operation of a threeway operating valve 6, which either admits high-pressure operating gas 7, such as compressed air, to the right-hand side 8 of the operating piston 9 for closing the breaker, or effects a reduction of pressure in the region 10 by dumping the same to the atmosphere through the port II. It will be noted that there is provided a grounded generally annular support housing 12 having fixedly secured thereto a laterally extending insulating casing 13, which secures the three-way operating valve 6 in a fixed position and, additionally, provides an operating cylinder 14, within which reciprocally moves the operating piston 9 carrying a tubular movable sleevelike contact structure l6.

Disposed within a pressurized region 18, defined by the aforesaid insulating casing 13, is a stationary contact structure 20 situate at the right-hand end 21 of a terminal bushing 22, through which extends a terminal stud 23 making electrical contact with a left-hand breaker terminal 25. A second tapered insulating casing 26 surrounds the left-hand end of the terminal bushing 22 and additionally defines the pressurized region 18, which may, for example, contain a suitable arcextinguishing gas, such as sulfur hexafluoride (SF gas, at a pressure of 75 to I00 p.s.i.g., for example.

Generally, the arrangement is such that upon a reduction of pressure on the right-hand side 8 of the operating piston 9, the pressure of the sulfur hexafluoride gas within region 18 will act through the region 27 interiorly of the movable tubular contact structure 16 on the left-hand face 29 of the operating piston 9, and thereby move it toward the right, effecting contact separation and simultaneously compression of the closing spring 30.

In addition, it will be noted that rightward opening movement of the piston 9 and movable tubular sleevelike contact 16 will create a cavitation, or a relatively low-pressure region within the space 51 in front of the piston 9. Since the movable tubular contact 16 is actuated by piston rods 16', sulfur hexafluoride (SF,,) gas will be drawn into the moving tubular contact l6 and into the cavitation region 51 during the opening operation.

It will be noted that the operating cylinder 14 and piston 9 movable therein constitute a cavitation device with the cavitation region 51 thereof communicating solely with the enclosed casing 13 by way of the movable tubular venting contact 16.

As illustrated more fully in FIG. 3 of the drawings, the three-way operating valve 6 may be rotated to its operating position by an insulating rod 31, which extends through an insulating tube 32, and is pivotally connected, as at 33, to a rotatable crank structure 34, the lower end of which is pivotally connected to a double-acting solenoid structure 35 having the two armatures 36, 37 thereof magnetically attracted by a pair of solenoid windings 38, 39, one of which may be a closing winding and the other a trip winding. These will be energized by the closing of a pair of close" and open" buttons 40, 41, as will be obvious to those skilled in the art.

As shown in FIG. I, the closing button 40 has been pressed and the closing solenoid 38 energized to thereby effect clockwise rotation of the operating crank structure 34 to thereby admit compressed operating fluid 7, such as compressed air, through a passageway 43 and to the right-hand side 8 of the operating piston 9 to effect contact closure. It will be noted that this closing action is assisted by the operation of the closing spring 30.

During the opening operation, an energization of the tripping solenoid 39 will effect counterclockwise rotative motion of the valve-operating crank 34 to thereby effect clockwise rotation of the valve 6 to thereby reduce, or dump the pressure on the right-hand side 8 of the operating piston 9 to thereby efiect contact separation, in a manner more clearly illustrated in FIG. 2 of the drawings.

With reference to FIG. 2, it will be noted that the separating movement of the tubular bridging sleevelike contact 16 from the stationary contact fingers will cause an are 45 to be established at the stationary arcing contact 20", and to cause the right-hand end of the established arc 45 to terminate upon a stationary tubular arcing contact structure 47. This is formed by a reentrant portion of a stationary electrostatic shielding structure 54, hereinafter described. Additionally, it will be noted that the movable tubular bridging main contact structure. 16, secured by piston rods 16 to the operating piston 9, will be moved toward the right into the annular region 49 of said reentrant portion, ,47 and will, by so doing, cause the are 45 to be established at a fixed optimum length suitable for rapid arc extinction by the passage of the high-- pressure gas 50 within the region 18, through the interior 27 of the stationary tubular reentrant contact portion 47, and into the cavitation region 51 on the left-hand side of the operating piston 9.

It will be observed, that the operating piston 9 is generally cup-shaped to not only accommodate the closing spring 30, but to additionally accommodate the rolling diaphragm 52. l preferably employ a Bellofra m diaphragm 52. As shown in FIG. I, it will be noted that the Bellofram diaphragm is folded back upon itself, as is permitted by such a device. The Bellofram diaphragm is a rolling-seal diaphragm, such as described in US. Pat. 2,849,026, issued Aug. 26, 1958, to John F. Taplin, and is sold by the'Bellofram Corporation located in Burlington, Massachusetts,. The Bellofram diaphragm provides abetter sealthan would be. obtained by utilizing O-rings sliding with the movable piston 9.

lt will be noted that the provision of the outer electrostatic stationary shielding structure 53, shown more clearly in FIG. 2, and encompassing the flexible stationary contact fingers 20, together with the provision of the stationary electrostatic shielding structure 54, providing the, aforesaid reentrant stationary contact portion 47, insures a uniformity of the electric field between the separated contact structure in the open-circuit position. This will tend to minimize the chance of electrical break-down in the open position. Additionally, the provi sion of the stationary tubular contact portion 47 will provide the optimum arc length for the arc 45, as set forth hereinbefore. Moreover, the location of the closing spring 30 and rolling diaphragm 52 in the annular space 10a behind the operating piston 9 will shield the diaphragm 52 and closing spring 30 from the hot arc gases, which are cooled by the cooling members 17 and 55 situated in the spaces 27 and 5l more clearly illustrated in FIG. -2 of the drawings. g

It will be observed that if the breaker I isin theopen-circuit position, as is illustrated in FIG. 2 of the drawings, and for any reason should the region 18 lose its pressure, the closing spring 30 in back of the piston will close the breaker to prevent possible sparkover across the separated contacts 16, 20. Another function of the closing spring 30 is to make it possible to keep the closing air pressure always less than the SF pressure so that the fold in the rolling diaphragm 52 will be always biased in the same direction.

FIGS. 4 and 5 show further novel contact modifications for more positive are drawing on the axis of the contacts by utilizing a movable arcing contact 57 secured to the operating piston 9, which also carries the movable tubular sleevelike main bridging contact 59 by piston rods 59'. In FIG. 4, this contact 57 enters a recess 60 provided in the stationary arcing contact 61. In FIG. 5, the arcing contact 61a, surrounded by the finger assembly 62, is resiliently mounted, being biased by a compression spring 63 toanextend position, and also provided with separate fingers or a flexible shunt (not shown) to conduct current from the contact 61a to the terminal 21. In either case, the main bridging contact 59 moves out of the contact fingers 62 first, transferring the current to the arcing contacts 61, 61a, 57, which separate a moment later to draw the are 45 on the axis in thedownstream gas flow, which interrupts the are at the next currentzero. The coolers, 17, 55, and 64, make possible highercurrent interruption by reducing clogging. As well known by those skilled in the art, the clogging results from an increase, of pressure within the stationary tubular arcing contact structure 47 due to gas expansion from heating by the arc, which impedes the. free flow of high-pressure gas into-and through the stationary tubular con- FIG. 6 illustrates a modification 66 of the invention in which I a pair of serially related separable contact Structures of the type illustrated in FIGS. 1 and 2 are utilized in the same breaker structure. By the use of two valve-operating rods 3!. the opening action can be made simultaneous in an obvious manner. This will enable a higher voltage rating to be attained. The manner of arc interruption is identical to that set forth hereinabove with reference to FIGS. 1-3 of the drawings.

Although there have been illustrated and described specific structures, it is to be clearly understoodthat the same were merely for the purpose of illustration. and that changes and modifications may readily be made therein by those skilled in the art without departing from thespi'rit and scope of the invention. I

We claim:

I. A compressed-gas circuit interrupter including means defining an enclosed casing containing gas under pressure, a

, relatively stationary contact structure and a cooperable movable tubular contact structure separable within said enclosed casing to establish arcing therebetween, said movable contact structure comprising a stationary metallic electrostatic shield having an annular reentrant portion formed therein within which reciprocates a movable sleevelike tubular contact. said stationary annular reentrant portion providing a forwardly (no I tending stationary tubular ventingarcing contact which extends more closely to said stationary contact structure than does said movable sleevelike tubularcontact toward the end of the opening operation of the interrupter. means causing a cavitation effect downstream of said stationary tubular arcing contact during the opening operation to cause thereby gas to flow through said stationary tubular venting arcing contact for effecting arc extinction, whereby a fixed open-position contact gap will exist during arcing tor limiting'the length of drawing of the established arc.

2. The combination of claim I. wherein the cavitation means comprises a movable piston mechanically connected to said movable sleevelike tubular contact and reciprocally operable within a stationary operating cylinder.

3. The combination of claim I. wherein a movable pinlikc arcing contact movable on the axis of the movable contact 1 structure moves simultaneously with-the movement of the commodate the movable pinlike arcing contact.

movable sleevelike tubular contact. I

4. The combination of claim I. wherein colling means are provided interiorly of the tubular stationary arcing contact.

5. The combination of claim 3. wherein cooling stationary contact structure comprises a relatively stationary arcing contact having an accommodating recess provided therein to ac- 6. The combination of claim I. wherein two such assemblies of stationary and movable cooperable contact structures are provided in series for the higher voltages and arranged for simultaneous operation.

7. The combination of claim 2. wherein means is provided to bias the movable piston to the contact closed position.

8.,The combination of claim 7. wherein a compression spring constitutes such biasing means. 

1. A compressed-gas circuit interrupter including means defining an enclosed casing containing gas under pressure, a relatively stationary contact structure and a cooperable movable tubular contact structure separable within said enclosed casing to establish arcing therebetween, said movable contact structure comprising a stationary metallic electrostatic shield having an annular reentrant portion formed therein within which reciprocates a movable sleevelike tubular contact, said stationary annular reentrant portion providing a forwardly extending stationary tubular venting arcing contact which extends more closely to said stationary contact structure than does said movable sleevelike tubular contact toward the end of the opening operation of the interrupter, means causing a cavitation effect downstream of said stationary tubular arcing contact during the opening operation to cause thereby gas to flow through said stationary tubular venting arcing contact for effecting arc extinction, whereby a fixed open-position contact gap will exist during arcing for limiting the length of drawing of the established arc.
 2. The combination of claim 1, wherein the cavitation means comprises a movable piston mechanically connected to said movable sleevelike tubular contact and reciprocally operable within a stationary operating cylinder.
 3. The combination of claim 1, wherein a movable pinlike arcing contact movable on the axis of the movable contact structure moves simultaneously with the movement of the movable sleevelike tubular contact.
 4. The combination of claim 1, wherein colling means are provided interiorly of the tubular stationary arcing contact.
 5. The combination of claim 3, wherein cooling stationary contact structure comprises a relatively stationary arcing contact having an accommodating recess provided therein to accommodate the movable pinlike arcing contact.
 6. The combination of claim 1, wherein two such assemblies of stationary and movable cooperable contact structures are provided in series for the higher voltages and arranged for simultaneous operation.
 7. The combination of claim 2, wherein means is provided to bias the movable piston to the contact closed position.
 8. The combination of claim 7, wherein a compression spring constitutes such biasing means. 